Vulcanization of rubber or the rubbery co-polymer of butadiene and styrene



l atente'd July 15, 1947 I UNITED STATES PATENT OFFICE I 2,424,175 Y Y VULCANIZATION or RUBBER on THE RUB- 1 'BEBY (JO-POLYMER or BUTADIENE AND smnnn v Paul 0. Jones, Silver Laka'aiianoz'er Mathes,

Goodrich Akron, Ohio, assignors to The B. 1.

.--Company, New Yo'rk,,N. Y.', a corporation of New York Y No Drawing. Application December- 8,

Serial No. 513,490

We have discovered that amino'alkyl sulfides er alkylene groups may be present if desired.

the vulcanization of R: and B: may be "aliphatic groups such a: alkyl, cycloalkyl, aralkyl, hydroxyalkyl, alkoxy alkyl, aminoalkyl, or haloalkyl groups, while R5" may also be an aromatic group. In the prehaving the general structural formula. 5 ten-ed groups of compounds, Rzand Ra are hydro- I carbong'roups oramino substitutedhydrocarbon groups. Inthe latter case wherein R1 is an organic radical 'with the free i, valence on a carbon atom, A is an'alkylene group 7 a a Ba with the free valences on difierent carbon atoms, is derived frompolyamine such as ethylene di- R: is a member of the class consisting of hydro en, amine, triethylene tetramine, para-phenylene diandaliphatic and aromatic groups attached to amine, etc. H I the nitrogen through a carbon atom, and R: is 1 Typical aminoaliwi sulfides within the scope an aliphatic group attached to the nitrogen .of this invention include: through a carbon-atom, are excellent accelerators. CH? h v The R1S portion 01 the compound may be regarded as the residue formed by removing the l 1 T' f H from the SH group of a sulihydryl com- Ht-S pound. Suitable sulihydryl compounds from I 2.thmunyiet'h};1ammoethy1sulfide. which the accelerators of this invention may be considered as derived include methyl mercaptan. 2411mmmethylammmhylsmflde' ethyl mercaptan, isopropyl mercaptan, allyl merz-thimllnylmethrlaminopronylsulfide, 2:13am: cyclohtexyl mercaptan, binhzlyl mercaapltain, 1 26 mmmlmy] dimethylammobums'umd,

op enoi, or ho, meta, or para ocresol, p a I or beta thionaphthol, l-thioanthrol, thioanthranMummymthylphmmmmmlWe nol, p-chiorthiophenol, p-m'e'thoxythiophenol, oy w in yls de. anllinothiophenol, methanecarbothiolic acid, z-thinmlinyidibutyiaminoethyisulflde, methanecarbodithioic acid, ethanecarbodithioic 30 acid, benzene-carbodithioic acid, 3-iuranecarbo- Z dithioic acid, ethyl-xanthogenic acid, dimethyldi- H8 CS-GH|-CHr-CHr-NH-CH: thiocarbamic acid, methyl-ethyl-dithiocarbamic wi ethyldithlwalbflmic c methylphenyl' 3-penthiazollnyl methylsminopropylsuiflde, 7, dithiocarbamic acid, ethyi-benzyl-dithiocarbamic I acid, diphenyldithiocarbamic acid, phenyl-alphanaphthyl-dithiocarbamic acid, phenyl-parachlorphenyl-dithiocarbamic acid, o,o'-dimethylmethylenediphenyldithiocarbamic' acid, phenyl- Y para hydroxyphenyl dithiocarbamic a. ci d, 40 e phenyl-anilino-phenyl-dithiocarbamic acid,- merethyhmmoeth'l captothiazole, mercaptobenzothiazole, mercapto- 2-benzothlazyl benzylaminoetbyl sulfide, benzoxazole, mercaptobenzimidazole, mercapto- ,rbmmfimyldiethymmmoemylsmnde, 4,5-dimethy1 thiazole, mercapto 4 methyl-S- ethyl-thiazole, mercapto-i-phenylthiazole, mervzmnwmuylchhmlammmthyxsumdh captothiazoline, mercapto-4,5-dimethylthiazoline, 2-benzothiazyl butylsminoethyl sulfide, mercaptopenthiazoline, mercaptometathiazine, Memothmm dibutyhmmmhyl sulfide mercaptooxazine, mercaptoquinoline, etc. GHPC N A is preferably-a lower alkylene group contain- .ing not over 6 carbon atomssuch as ethylene, propylene, Z-methyiethylene, etc., although high- 011,- -s

I 4,6-dlmethy1thiuy1 ethyiaminoethyl sulfide,

C-8CHr-cHrrNK-CHr-CHr-NH-rCHPOHrS-C Diphenylthiocarbamyl ethylaminoetiiylauliide amino ethyl ohlorideare boiled under reflux (at about 102 C.) with aslight'excess over two molar proportions of a 40% water solution of caustic alkali. The reaction is substantially *complete after 4 hours. The z thiazolinyl butylaminoethyl sulfide which is formed is anyoil which separates from the water and needs only to be washed-with more water and dried. 'The other compounds referred to herein may be'prepared in the same way by selection ofthe appropriate raw-materials in each case.

As a specific example of the method of this i'nvention, accelerators'within the class herein defined were inporporated. in the following-rubber composition:

Rubber 100 7 Carbon black 51.5 Zinc oxide 10 Laurie acid 3 Sulfur 3 Antioxidant I 0.75 Acceleraton, 1.5

When the rubber compositions were cured for 45 minutes at 265 F., vulcanizates having the following propertieswere obtained, T representing tensile strength at break in lbs/in. and E representing ultimate elongation in per cent:

Accelerator T E Z-thiazolinyl butylaminoethyl sulfide -2, 300 610 butylammoethyl ester of a mixture of 4,5-dimethyl mercaptothiazole and 4-ethyimercaptoth1azole. 2. 700 570 As another example, accelerators were incorporated in the following synthetic rubbercomposition, in which they were activated by a secondary accelerator:

GH (butadiene-styrenecopolymer)- 100 Carbon black 50 Zinc oxide 10 Sulfur 2 Antioxidant 1 2,4 dinitrophenyl dimethyldithiocarba nate 0.4 Accelerator 1 When the compositions were; cured for 45.min-

N ,N -bis-4-4,5-dimethylthiuy1thioethyi ethylene diamiue 2-mercaptp'benzothiazol e (control) Q 1,650 .2-benzothiazylbutylammoethyl sulfide 1,233

butylaminoethyl ester of a mixture of 4,5-dimethyl -2-thiazoliuyl dibutylaininoethyl sulfldeti I:

utes at 265 vulcanizates having the following properties were obtained:

l Accelerator T E -2-benzothiazyl dibutylaminoethyl sulilde dibutylaniinoethyl ester oi a mixture oi 4,5 dimethyi mercaptothiazole and 4-eth l mercaptothiazole. v l; 650

mercaptotliiazoleand i-ethyl mercaptothiazole i, 500 490 480 2-thiazolmyl butylamiuoethy sulfide It is particularly noteworthy that these new accelerators give-rise to stocks having markedly vgreaterultimate elongation than those containing conventional accelerators such as Z-mercapto benzothiazole, and having a comparable or greater strength, thus overcoming one of the disadvantages ofythis type of synthetic rubber.

It will be noted that lauric acid was included inthe above compositions. It is generally true of the accelerators of this invention, however, that they dofnot require any acid to effect good cures, regardless of the activity of the compounds fromwhich they are derived.

It is to bezunderstood that the specific examples given above are merely illustrative of one manner ofthe use of the accelerators of this inventionflthat other accelerators within the scope of the class herein defined may be substituted for the specific compounds used in the examples; that the accelerators of this invention may be used to vulcanize not only natural rub-' her or caoutchouc but also balata, gutta percha,

synthetic rubber of the types which undergo vulcanization when heated with sulfur, vor natural "orartificially prepared latex; that the -accelerators may be incorporated in the rubber by mastication ormilling, or in the caseof latex or other dispersion or solution, by simply dissolving or suspending the accelerator therein; that the accelerators-may be used in admixture with each other or with other known accelerators or with antioxidants, organic acids, amines, softeners,

activatorsf retarders, pigments, fillers, etc.;-and that the rubber may be vulcanized with the assistance of this new class of accelerators in heat- .ed molds, hot air, steam, hot water, etc. The accelerators of this invention may advantageously be used in as-lowaproportionas 0.05% of the rubber in the composition, in which case 3 to 5% of sulfur isgenerally required or as high a 5%, with a much reduced quantity of sulfur.

j This invention is accordingly not limited to the specific examples herein set forth, for it will be obvious-to those skilled in the art that many modifications such as using other materials having equivalent properties and varying the proportionsof materials used are within the spirit and scope of'the invention as defined in the appended claims.

Thisis a continuation in part of our copending applicationSerial No. 307,635, filed December 5, 1939.

We claim:

1. .The method which comprises vuicanizing a vulcanizablematerial selected from the class consistingof rubber and butadiene styrene copolymer synthetic'rubber in the presenceotz to 5% by weight based on the vulcanizable material of $111- furand in the additional presence of- 0.05 to by weight based on the vulcanizable material of a compound having the structural formula wherein R1 is an organic radical with the free valence on a carbon atom, A is an alkylene group with the free valences on different carbon atoms, R: is a member of the class consisting of hydrogen, and aliphatic an aromatic groups attached to the nitrogen through a carbon atom, and R: is an aliphatic hydrocarbon group.

2. The method which comprises vulcanizing a vulcanizable material selected from the class consisting of rubber and butadiene styrene copolymer synthetic rubber in the presence of 2 to 5% by weight based on the vulcanizable material of sulfur and in the additional presence of 0.05 to 5% by weight based on the vulcanizable material of a compound having the structural formula R: R1-SA-N/ wherein R1 is an organic radical with the free valence on a carbon atom, A is an alkylene group containing not over six carbon atoms and with the free valences on different carbon atoms, R2 is hydrogen and R3 is an aliphatic group attached to the nitrogen through a carbon atom,

3. The method which comprises vulcanizing rubber in the presence of 2 to 5% by weight based on the rubber of sulfur and in the additional presence of 0.05 to 5 by weight based on the rubber of a thiazyl alkylaminoethyl sulfide.

4. The method which comprises vulcanizfng a butadiene styrene copolymer synthetic rubber in the presence of 2 to 5% by weight based on the synthetic rubber of sulfur and in the addi-.- tional 'presence of 0.05 to 5% by weight based on the synthetic rubber of a thiazyl alkylaminoethyl sulfide.

' 5. The method of claim 4 wherein the thiazyl alkylaminoethyl sulfide is 2-benzothiazyl alkylaminoethyl sulfide.

6. The method which comprises vulcanizing a vulcanizable material selected from the class consisting of rubber and butadiene styrene copolymer synthetic rubber in the presence of 2 to 5% by weight based on the vulcanizable material of sulfur and in the additional presence of 0.05 .to 5% by weight based on the vulcanizable material of a Z-thiazolinyl alkylaminoethyl sulfide.

7. The method which comprises vulcanizing butadiene styrene copolymer synthetic rubber in the presence of 2 to 5% by weight based on the synthetic rubber of sulfur and in the additional presence of 0.05 to 5% by weight based on the synthetic rubber of a compound having the structural formula wherein R1 is an organic radical with a free valence on a carbon atom, A is an ethylene group,

is an alkyl-hydrocarbon substituted amino group.

8. An unvulcanized composition containing a predominant amount of a material selected from the class consisting of rubber and butadiene styrene copolymer synthetic rubbe and also containing sulfur and from 0.05 to 5% by weight based on the said material of a compound having the structural formula wherein R1 is an organic radical with the free valence on a carbon atom, A is an alkylene group with the free valences on different carbon atoms, R: is a membe of the class consisting of hydrogen, and aliphatic and aromatic groups attached to the nitrogen through a carbon atom, and Ra is an aliphatic hydrocarbon group.

9. An unvulcanized composition containing a predominant amount of a material selected from the class consisting of rubber and butadiene styrene copolymer synthetic rubber and also containingsulfur and from 0.05 to 5% by weight based on the said material of a compound having the structural formula 'wherein R1 is an organic radical with the free valence on a carbon atom, A is an alkylene group containing not over six carbon atoms and with the free valences on different carbon atoms, Ra is hydrogen and R3 is an aliphatic group attached to the nitrogen through a carbon atom.

10. An unvulcanized rubber composition containing a predominant amount of rubber together with sulfur and from 0.05 to 5% by weight based on the rubber of a thiazyl alkylaminoethyl sulfide.

11. An unvulcanized synthetic rubber composition containing a predominant amount of butadiene styrene copolymer synthetic rubber together with sulfur and from 0.05 to 5% by weight based on the synthetic rubber of a thiazyl alkylaminoethyl sulfide.

12. The composition of claim 11 wherein the thiazyl'alkylaminoethyl sulfide is a 2-benzothiazyl alkylaminoethyl sulfide.

13. An unvulcanized composition containing a predominant amount of a material selected from the class consisting of rubber and butadiene styrene copolymer synthetic rubber and also containing sulfur and from 0.05 to 5% by weight based on the said material of a. 2-thiazolinyl alkylaminoethyl sulfide.

' PAUL C. JONES.

ROGER A. MATHIES.

REFERENCES CITED UNITED STATES PATENTS Number Name Date Jones Oct. 24, 1939 Certificate of Correction Patent No. 2,424,175. July 15, 1947.

PAUL C. JONES ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Column 3, line 5, for that part of the compound reading N,N-bis-4-4,5- read N ,N -bis-4,5-; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 16th day of December, A. D. 1947.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

